Loose insert or continuous mailers are well known in the art. These mailers are normally used in business to send out invoices or other information normally requiring a response. In this respect, the mailer will usually include a mailing envelope with a return envelope inside the mailing envelope.
Such combined envelopes are normally mass produced by a continuous manufacturing process involving the movement of over-lying plys of paper along a conveyor system wherein appropriate glueing or heat sealing operations are carried out as well as provision of cut-outs in the outer or mailing envelope facilitating opening of the same to gain access to the interior. Often times there are provided perforations instead of cut-outs to define a tear tab which can be easily removed to gain access to the interior of the envelope.
In all constructions of which I am aware, such tear tabs are defined by parallel spaced perforations running along a longitudinal edge of the envelope. An example of one such continuous mailer is shown in U.S. Pat. No. 4,157,759. The continuous mailer described in this patent illustrates clearly a perforated pull tab along the rear top longitudinal edge of the envelope. This tab is designed to remove simultaneously a protective covering of the flap seal for the return envelope. As a result, the removal of the outer tab to gain access to the interior automatically conditions the return envelope for immediate sealing and mailing back to the sender.
Where perforations run longitudinally along an evelope mass produced by movement along the direction of the width of the envelope, the movement of the web or various plys in producing the same must be slowed substantially while the perforations along the length of the envelope are formed. Further slowing occurs when longitudinal glue lines must be added to a return envelope flap.